Richmond has the highest proportion of poorly-insulated homes in the capital, research has revealed.
Seven in 10 families in the south-west London borough are living in homes with energy efficiency ratings between EPC bands D and G.
About 71 per cent of homes in Richmond fall into the lowest energy efficiency range — at a staggering cost of £13.4 million.
Tower Hamlets, Havering and Enfield are tied in second place with 66 per cent, while Kingston and Bromley follow just behind at 64 per cent.
It comes as analysis by the Liberal Democrats shows that 13.4 million homes across the UK have received poor efficiency ratings, costing families more than £12 billion a year for their energy bills.
Households in bands D to G pay an average of £931 a year more than those with a Band C rating. Meanwhile, those in Band G pay nearly £1,350 more each year.
Across the UK, those living in the Isles of Scilly have some of the worst insulated homes, with 85 per cent of homes in bands D to G.
Four in five families in Pembrokeshire and Gwynedd are in poorly-insulated homes, paying an estimated £60.7 million more a year than those in Band C, while three-quarters of Blackpool residents are paying about £54.5 million more for their draughty homes.
In Richmondshire — which contains Prime Minister Rishi Sunak’s Yorkshire constituency of Richmond — six in 10 families live in poorly-insulated homes, costing an extra £45 million.
Liberal Democrat climate and energy spokeswoman Wera Hobhouse MP said: “This Conservative Government’s failure to tackle our cold and leaky homes has piled misery on top of the cost-of-living crisis. It has left families around the country struggling to heat their homes and put food on the table.
“Now is the time for this new Conservative Prime Minister to make our homes warmer. If they don’t we are facing another energy crisis in the future.
“An emergency package of support is needed to fix Britain’s leaky homes and cut energy bills in the long term.”